Abstract
This paper is an analytical study of peristaltic motion of an incompressible newtonian fluid through a channel in the presence of three layers flow with different viscosities. We use a small Reynolds number and long wavelengths approximations to solve the system of the governing equations. The interfaces shapes are described by a system of non-linear fourth-order algebraic equations. We solve this system numerically. We present a detailed analysis of the effects of both peripheral and intermediate layers on the fluid motion. The effect of the variation of the two viscosities on the mechanical efficiency has been studied. The trapping limits are found. Also, the variation of trapping width with the variation of the volume flow rate has been investigated. It has been noticed that the shape of interfaces, the pumping performance and the mechanical efficiency affect by the variation of the viscosity of the peripheral layer more than the variation of the viscosity of the intermediate layer.